End point detection electrode system and etch station

ABSTRACT

An end point detection electrode system and an etch station including the electrode system are disclosed. In one embodiment, the electrode system includes: an insulative mount; a first Mu-metal electrode coupled to the insulative mount; and a second Mu-metal electrode coupled to the insulative mount, the second electrode surrounding the first electrode.

BACKGROUND

1. Technical Field

The disclosure relates generally to integrated chip (IC) fabrication, and more particularly, to an end point detection electrode system.

2. Background Art

As integrated circuit devices increase in device density and the size of wafers used in integrated circuit manufacturing increase in size, there is a continued need for more precise manufacturing process control.

In wet processes (e.g., wet etching) used in some stages of integrated circuit manufacture, process endpoint control has been achieved by monitoring one or more electrical properties (e.g., impedance) in the liquid bath medium in which the wet process is conducted. The change of such electrical property(ies) is correlated to the actual state of the wafer(s) being processed such that the process can be terminated or altered when a target electrical property value and/or rate of change is achieved. Examples of such processes are described in U.S. Pat. Nos. 5,338,390; 5,445,705; 5,451,289; 5,456,788; 5,480,511; 5,501,766; 5,516,399; 5,788,801; and 6,843,880, the disclosures of which are incorporated herein by reference.

One electrode system used in the above patents includes two linear and parallel electrodes. While the known technique provides some process control, it can be difficult to interpret the electrical signal corresponding to the monitored electrical property using the current electrode systems. For example, current IC chip fabrication techniques use a large variety of etch recipes and function at such small dimensions that current electrode systems are inadequate. In particular, current electrode systems do not provide a signal of adequate amplitude, and may be too sensitive to wafer orientation, and part-to-part variation to produce reliable monitoring feedback. These problems can lead to operator and/or machine error in interpreting when to stop the wet process of interest such that the ideal manufacturing result is not achieved, e.g., over-etching or under-etching occurs.

SUMMARY

An end point detection electrode system and an etch station including the electrode system are disclosed. In one embodiment, the electrode system includes: an insulative mount; a first Mu-metal electrode coupled to the insulative mount; and a second Mu-metal electrode coupled to the insulative mount, the second electrode surrounding the first electrode.

A first aspect of the disclosure provides an end point detection electrode system comprising: an insulative mount; a first Mu-metal electrode coupled to the insulative mount; and a second Mu-metal electrode coupled to the insulative mount, the second Mu-metal electrode surrounding the first Mu-metal electrode.

A second aspect of the disclosure provides an etch station comprising: a wet etchant bath; an end point detection electrode system including: an insulative mount, a first Mu-metal electrode coupled to the insulative mount, and a second Mu-metal electrode coupled to the insulative mount, the second electrode surrounding the first electrode; and means for monitoring an electrical characteristic between the first Mu-metal electrode and the second Mu-metal electrode and controlling the etching process based on the monitoring.

The illustrative aspects of the present disclosure are designed to solve the problems herein described and/or other problems not discussed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this disclosure will be more readily understood from the following detailed description of the various aspects of the disclosure taken in conjunction with the accompanying drawings that depict various embodiments of the disclosure, in which:

FIG. 1 shows one embodiment of an end point electrode system according to the disclosure.

FIG. 2 shows one embodiment of an etch station including the end point electrode system of FIG. 1.

It is noted that the drawings of the disclosure are not to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings.

DETAILED DESCRIPTION

Referring to FIG. 1, one embodiment of an end point detection electrode system 100 according to the disclosure is shown. End point detection electrode system 100 (hereinafter “electrode system 100”) may include an insulative mount 102, which may be coupled to a mechanism (not shown) for moving electrode system 100 into and out of wet etchant bath 104 (FIG. 2). Insulative mount 102 may include any insulative material, but, in one embodiment, includes polyvinyl chloride (PVC).

A first Mu-metal electrode 110 is coupled to insulative mount 102, and a second Mu-metal electrode 112 is also coupled to insulative mount 102. Each electrode 110, 112 may be coupled in any fashion, e.g., embedding in insulative mount 102, adhesive, etc. “Mu metal” may include, for example, any highly magnetic permeable material, which makes it effective at screening static or low-frequency magnetic fields. In one embodiment, Mu-metal may include, for example, a nickel-iron-copper-molybdenum alloy (e.g., with 75% nickel, 15% iron, plus copper and molybdenum) that has a very high magnetic permeability. Other formulations of Mu-metal may also be employed within the scope of the disclosure. As illustrated, second Mu-metal electrode 112 surrounds first Mu-metal electrode 110. In one embodiment, first Mu-metal electrode 110 is substantially circular, and second Mu-metal electrode 112 is substantially O-shaped. However, the disclosure is not limited to circular or O-shaped electrodes. First and second Mu-metal electrodes 110, 112 may be substantially coaxial.

Although a variety of dimensions may be employed, in one embodiment, electrode system 100 is sized so as to accommodate a 300 mm wafer 120 (FIG.2). In this case, first Mu-metal electrode 110 may have a diameter D1 of approximately 1.8 inches to approximately 2.2 inches, and preferably approximately 2 inches, with “approximately” in the range of ±0.1 inches. Second Mu-metal electrode 112 may have an inner diameter D2 of approximately 3.8 inches to approximately 4.2 inches and an outer diameter D3 of approximately 4.8 inches to approximately 5.2 inches, with “approximately” in the range of ±0.1 inches.

Electrode system 100 is less susceptible to wafer orientation and part-to-part variation and exhibits improved signal amplitude, i.e., it is less sensitive to noise. As a result, electrode system 100 provides improved processing, reduced cycle time and less chemical usage.

FIG. 2 shows one embodiment of an etch station 200 according to one embodiment of the disclosure. Etch station 200 includes a wet etchant bath 104, which may include any wet etching liquid now known or later developed. End station 200 includes an end point detection electrode system 100, as described above. As understood, end station 200 may also include any now known or later developed system(s) 130, 132 for monitoring an electrical characteristic between first Mu-metal electrode 110 and second Mu-metal electrode 112 and for controlling the etching process based on the monitoring. Systems 130, 132 may include, for example, computerized analysis systems to determine factors such as end point detection, etch rate, average etch rate, etc., and/or robotic controllers to control movement and etching of wafer 120 and/or electrode system 100.

The systems and etch stations as described above are used in the fabrication of integrated circuit chips. The resulting integrated circuit chips can be distributed by the fabricator in raw wafer form (that is, as a single wafer that has multiple unpackaged chips), as a bare die, or in a packaged form. In the latter case the chip is mounted in a single chip package (such as a plastic carrier, with leads that are affixed to a motherboard or other higher level carrier) or in a multichip package (such as a ceramic carrier that has either or both surface interconnections or buried interconnections). In any case the chip is then integrated with other chips, discrete circuit elements, and/or other signal processing devices as part of either (a) an intermediate product, such as a motherboard, or (b) an end product. The end product can be any product that includes integrated circuit chips, ranging from toys and other low-end applications to advanced computer products having a display, a keyboard or other input device, and a central processor.

The foregoing description of various aspects of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and obviously, many modifications and variations are possible. Such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of the disclosure as defined by the accompanying claims. 

1. An end point detection electrode system comprising: an insulative mount; a first Mu-metal electrode coupled to the insulative mount; and a second Mu-metal electrode coupled to the insulative mount, the second Mu-metal electrode surrounding the first Mu-metal electrode.
 2. The system of claim 1, wherein the insulative mount includes polyvinyl chloride (PVC).
 3. The system of claim 1, wherein the first Mu-metal electrode is substantially circular, and the second Mu-metal electrode is substantially O-shaped.
 4. The system of claim 3, wherein the first Mu-metal electrode has a diameter of approximately 1.8 inches to approximately 2.2 inches, and the second Mu-metal electrode has an inner diameter of approximately 3.8 inches to approximately 4.2 inches and an outer diameter of approximately 4.8 inches to approximately 5.2 inches.
 5. The system of claim 1, wherein the first and second Mu-metal electrodes are substantially coaxial.
 6. An etch station comprising: a wet etchant bath; an end point detection electrode system including: an insulative mount, a first Mu-metal electrode coupled to the insulative mount, and a second Mu-metal electrode coupled to the insulative mount, the second electrode surrounding the first electrode; and means for monitoring an electrical characteristic between the first Mu-metal electrode and the second Mu-metal electrode and controlling the etching process based on the monitoring. 